Ideally, a window and door system would be totally manufactured as a unitary system and put in place in the wall opening on the job site. The problem is that the size of window and door systems is such that it is not manageable to ship an entire assembled window and door system to a job site for installation. Accordingly, the typical window and door system will be manufactured in component parts which then will be assembled on the job site. This approach has the potential of assembly problems occurring which may result in a defective window and door system. What is desirable, then, is a window and door system that can be manufactured as fully as possible but yet be of such a size that it can be readily shipped to the job site and then installed on a basis that there is a minimal opportunity for mistakes to be made which will cause the system to be inoperative.